had excellent success by this procedure. Fig. 88 illustrates a case of musculospiral paralysis in which 4 inches of the nerve were completely shot away, and in which the gap was bridged by the external saphenous nerve. Complete return of the motor power resulted five months after the operation.

In

FIG. 89. Two photographs illustrating the effect of transplanting the dorsal sensory branch of the ulnar nerve to bridge a gap in the parent trunk, 11⁄2 years subsequent to the operation. a, To show the absence of atrophy of the hypothenar muscles. b, The power of spreading the fingers apart and the absence of atrophy of the interossei. There was anesthesia of the dorsum of the little finger and ulnar border of the hand but normal sensation over the palmar surface, indicating the growth of sensory fibers along the transplanted nerve.

another case of ulnar nerve paralysis, in which the dorsal branch of the ulnar nerve was used to bridge the gap, function returned eight months after the operation and the atrophy of the interossei present at the time of the operation disappeared a year and a quarter later (see Figs. 89a and b).

In all cases of nerve suture, the operator must preclude the possibility of the reformation of scar tissue about the nerve by changing its position. This can usually be accomplished by transplanting the nerve as already explained on page 118.

Whether it is advisable, in addition, to enclose the sutured nerve with fascia, cargile membrane, or hardened artery, is one of the numerous questions relative to the operative technic which awaits the answer of accurate experimental investigation.

5. When there is intraneural pressure, due to a hæmatoma or foreign body, the nerve should be slit longitudinally so as to cause minimal traumatization, the tumor removed, and the perineurium reunited by fine transverse stitches.

Operative Exposure of the Nerves. Of course, in all nerve operations, the general principles of rigid asepsis and minimal

traumatization must be rigidly adhered to. Never grasp the nerve roughly with forceps; always lift it gently by the perineurium; never allow it to dry; never free it unnecessarily from the surrounding tissue. The instruments should correspond in delicacy to the nature of the work required. The finest forceps, needles and suture material should be used. The instrument shown in Fig. 90-the stirrup clamp-is of particular value in lifting the nerve from its bed; by releasing the catch, the stirrup can be opened, the nerve brought over the lower bar, and when again closed, the nerve can be held taut without danger of injuring it. The operation should be performed without the Esmarch bandage, to be sure that no postoperative hæmorrhage occurs.

As a rule, with practically no exceptions, no attempt should be made to expose the nerve at the point of injury, since it is

here embedded in scar tissue and frequently is so degenerated as to be non-recognizable. It is much simpler to expose it above and below the lesion, and then work toward this central point. To find the nerve quickly and accurately, it is necessary to have exact anatomical knowledge of the course of the nerve with especial reference to the muscular cleavage planes. The following suggestions for the operative exposure of the nerves have proven of value to my students.

Musculospiral Nerve. This is readily found near the bend of the elbow by a longitudinal incision along the inner margin of the brachioradialis muscle (supinator longus). The incision is deepened between the supinator on one side and the brachialis anticus on the other side. The nerve is found between these two muscles. Care must be taken not to confuse it with the musculocutaneous nerve, which lies near the musculospiral at this point, although on a more superficial plane. They are readily distinguished by following the nerves upward, when the musculocutaneous is seen to emerge from between the brachialis anticus and the biceps, whereas the musculospiral passes backward.

It is difficult to locate the musculospiral in its course back of the humerus, since it is here deep under the muscles and there is no certain guide to its position. It is, however, readily found in the upper portion of its course by bluntly separating the long head of the triceps from the external head. Therefore, in injuries to the musculospiral it is well to expose it at this point and at the elbow, and follow the nerve upward and downward to the point of injury.

Of the two branches of the musculospiral nerve, the radial and posterior interosseous, only the former has surgical significance, since the posterior interosseous divides into numerous fine filaments at such a high point that its suture is seldom, if ever, feasible. The radial nerve can be used with great advantage for transplantation purposes, since its loss occasions little or no disturbance of sensation. It can be found by retracting the brachioradialis muscle (supinator longus) toward the radial side.

Median Nerve. In the upper arm this nerve is easy to identify because of its immediate relation to the brachial artery.

No surgical significance attaches to the crossing of the nerve and artery, so frequently emphasized in the anatomical textbooks, since the two structures are so intimately associated that the least traction with the forceps brings the nerve to the inner or to the outer side of the vessel. At the elbow, the nerve lies almost directly in the midline and is exposed by dividing the expansion of the biceps to the inner portion of the fascia (Lacertus fibrosus) when it is found passing into the arm between the two heads of the pronator radii teres. The deep head of the muscle separates the nerve from the ulnar artery. About 1 inch above the elbow, the branch to the pronator radii teres and flexor carpi radialis emerges from the parent trunk. Care should be taken not to injure it.

At the wrist, the nerve is found just to the ulnar side of the flexor carpi radialis tendon. It passes beneath the annular ligament just to the ulnar side of the flexor sublimis tendon to the index-finger.

Ulnar Nerve. This lies about one-quarter of an inch posterior to the artery in the upper half of the arm and then passes backward to the well-known groove in the internal condyle of the humerus. Throughout most of its course it lies posterior to the fascial septum separating the anterior from the posterior groups of muscles.

For a short distance below the elbow, it is difficult to find the nerve because it is buried in the fibres of the extensor carpi ulnaris; but in the lower two-thirds of the arm it is easily discovered by using the flexor carpi ulnaris as a guide. The nerve lies just to the radial side of this muscle and its tendon. About 4 or 5 inches above the wrist, the dorsal sensory branch passes backward. It is of significance for transplantation purposes, in case it is necessary to bridge a gap between the ends of the divided nerve.

Musculocutaneous.-The emergence of this nerve between the brachialis anticus and the biceps near the bend of the elbow, has already been referred to in describing the musculospiral The upper portion of the nerve is laid bare by separating the coracobrachialis from the short head of the biceps. Internal Cutaneous.-Like the radial, this is of significance for transplantation purposes, particularly when bridging a

nerve.

Its

gap in the ulnar or median nerves in the upper arm. position varies somewhat, but it is usually found between the ulnar and the median.

The Circumflex Nerve.-Operative exposure of this nerve is very seldom necessary in military surgery. The lower end of the brachial plexus has to be exposed by upward retraction of the pectoralis major and the nerve identified as it passes off the posterior trunk of the plexus.

The Brachial Plexus.-Ample operative exposure is given only by a long incision running from a point 4 inches above the clavicle to the axilla. The clavicle is divided by a Gigli

Sciatic nerve

Biceps (long head)
femoris

FIG. 91.-Diagram illustrating the relation of the great sciatic nerve to the long head of the biceps femoris muscle. To expose the nerve in the upper third of the thigh, the outer border of the muscle is found and drawn inward. In the lower half of the thigh the inner border is found and drawn outward.

saw, and the two ends are retracted. Great care must be exercised when freeing the plexus from the great vessels, and the operation should never be undertaken except by a surgeon experienced in vascular technic.

Sciatic Nerve. When exposure near the sacro-sciatic foramen is necessary, the best incision runs from the midline of the thigh at the lower border of the gluteus maximus over to the trochanter and upward with a sweep toward the midline near the upper border of the muscle. The skin muscle flap is retracted inward giving free exposure of the upper portion of the nerve. Some hæmorrhage is encountered in dividing